Satisfaction with orthodontic treatment: cross-cultural adaptation and validation of an instrument for the Brazilian Portuguese language

ABSTRACT Objective: To cross-culturally adapt into the Brazilian Portuguese and evaluate the psychometric properties of an instrument for assessing the satisfaction of parents/guardians regarding their sons’/daughters’ orthodontic treatment. Methods: Translations of the instrument from English, pre-test and evaluation of validity and reliability of the Brazilian Portuguese version were performed. The questionnaire has 25 items distributed across 3 subscales (process, psychosocial effect and outcome). Eighty-three parents/guardians of children/adolescents who had completed orthodontic treatment participated. Descriptive statistics and floor and ceiling effects were calculated. Internal consistency, stability (interval of three weeks), convergent construct validity and discriminant construct validity were determined. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) assessed dimensionality. Results: Among the 83 parents/guardians, 58 (69.9%) were mothers and 25 (30.1%) were fathers of children/adolescents. In the questionnaire’s total score and the three subscales scores, an acceptable percentage (≤15%) of participants achieved the maximum score (ceiling effect). In the total questionnaire score and in the three subscales scores, no participant achieved the minimum score (floor effect). Cronbach’s α coefficient for the total score was 0.72 (internal consistency). Intra-class correlation coefficient for the total score was 0.71 (stability). The questionnaire’s total score presented large Pearson correlation coefficient (>0.50) with the three subscales too (construct validity). Female parents/guardians had significantly higher scores in the psychosocial effect (p=0.013) and in the treatment outcome (p=0.037) subscales, compared to male parents/guardians (discriminant validity). EFA and CFA confirmed dimensionality in a three-factor solution. Conclusions: The final obtained version is valid and reliable to be used in Brazilian populations.


INTRODUCTION
Interest in patient satisfaction with health care has grown in recent years. 1 Patients' perceptions and expectations have become increasingly important to justify the provision of healthcare services and guarantee its general quality. 2 Measuring the satisfaction associated with orthodontic treatment process is complex, as multiple dimensions of treatment must be considered simultaneously. 1 Generally, the level of satisfaction with orthodontic treatment is assessed by the individual's perception of the final alignment and leveling of his/her teeth or only by the result of the treatment itself, being assessed through simple questionnaires or questionnaires developed for general dental practice. However, the result of orthodontic treatment does not involve just aligning and leveling the teeth or having good occlusion. Therefore, there is a need for a more comprehensive questionnaire that provides data that allow clinicians and orthodontic care service organizers to reflect on the specific level of satisfaction with the orthodontic treatment. 3 In a systematic review carried out in 2015, several factors associated with satisfaction in orthodontic treatment of patients and their guardians after completion of treatment were identified. In general, satisfaction was associated with pleasant aesthetic results perceived by patients, perception of psychological benefits with the treatment and good quality of care related to the interactions of patients with the orthodontist and his/her team. 4 However, in Alvarenga RN, Paiva SM, Flores-Mir C, Bernabé E, Abreu LG -Satisfaction with orthodontic treatment: cross-cultural adaptation and validation of an instrument for the Brazilian Portuguese language 5 most studies, the assessment of satisfaction with orthodontic treatment was performed with surveys with a limited number of questions, whose psychometric properties had not been validated. Moreover, in the Brazilian Portuguese language, there is no validated questionnaire that addresses orthodontic outcomes. 4 Bennett et al. 1  The original questionnaire in English language is a specific condition instrument developed in North Carolina, United States, created to assess the satisfaction of parents/guardians of individuals under 18 years of age who had undergone orthodontic treatment. This instrument consists of 25 questions distributed across 3 subscales: satisfaction with the treatment process (13 items), psychosocial effect of the treatment (7 items) and treatment outcome (5 items). Each item has 5 response options, according to the Likert scale, ranging from 1 to 5 (1=strongly disagree, 2=disagree, 3=neither agree nor disagree, 4=agree and 5=strongly agree).
The scores for the response of items 11 and 25 should be reversed (Appendix 1). The questionnaire's total score ranges between 25 and 125. The higher the score, the greater the satisfaction of the parent/guardian with the child's/adolescent's orthodontic treatment. The scores of the subscales range as follows: treatment process (13 -65), psychosocial effect of treatment (7 -35) and treatment outcome (5 -25). The higher the score, the greater the satisfaction of the parent/guardian with respect to the construct assessed in the subscales. 1

TRANSLATION AND CROSS-CULTURAL ADAPTATION OF THE INSTRUMENT
The stages of this study followed international standards for translation, cross-cultural adaptation and validation of instruments 5 for the assessment of health outcomes. After performing the back-translation, this English version produced by the back-translator was sent to the authors of the original instrument who did not suggest any modifications in the back-translated questionnaire. After all this process, a version of the instrument in the Brazilian Portuguese language was set (Appendix 2).
Alvarenga RN, Paiva SM, Flores-Mir C, Bernabé E, Abreu LG -Satisfaction with orthodontic treatment: cross-cultural adaptation and validation of an instrument for the Brazilian Portuguese language 8 After reaching a Brazilian Portuguese version, a pre-test was performed with a convenience sample of 15 parents/guardians of individuals under 18 years of age who had completed orthodontic treatment. Pre-test participants were not included in the main study. The purpose was to find possible difficulties in understanding the instrument by laypersons without a background in oral health practice. They were encouraged to suggest any synonyms for terms or words that were difficult to understand. A flowchart illustrating the complete process of translation, cross-cultural adaptation and validation of the instrument is provided in Figure 1.

PORTUGUESE VERSION
The main sample of this study comprised 83 parents/guardians of children/adolescents under the age of 18 who had completed orthodontic treatment in two orthodontic clinics. As inclusion criteria, these individuals had to be native Brazilian Portuguese speakers. Children/adolescents could not have craniofacial anomalies or cognitive disorders.  were clustered together. Confirmatory factor analysis (CFA) was performed to ratify the dimensionality of the questionnaire.
The Comparative Fit Index (CFI) was determined, and a value >0.90 denotes a satisfactory model fit. 12,13

RESULTS
Among the 83 parents/guardians who participated, 58 were women and 25 were men. Children's/adolescents' mean age was 13.0 years (±3.07) -41 were boys and 42 were girls. Sample's sociodemographic characteristics, malocclusion severity and the type of orthodontic treatment received by children/adolescents are shown in Table 1.   naire's total score and in the three subscales, the percentage of individuals reaching the minimum score was of 0% (Table 4). The value of KMO=0.743 and the significance of the Barlett's test of sphericity (p<0.001) confirmed the feasibility of the EFA. A graph displaying the relationship between the component numbers and the eigenvalues is showed in Figure 2.
The three-factor solution explained 59.35% of the overall vari-      are correlating well. 9 The total score of the questionnaire showed a Cronbach's α coefficient greater than 0.70. For the subscales, the values were close to this limit for acceptability, with only two subscales with values slightly lower than the threshold. In the study for the development of the original instrument in English, Cronbach's α coefficients were also greater than 0.70. It is noteworthy that this coefficient is strongly influenced by the number of items in the subscale and the sample size. 20 However, even if we consider the cutoff of acceptability as a rule of thumb, a slightly diminished Cronbach α coefficient does not necessarily imply that the questionnaire is unsatisfactory. 21 The reliability of an instrument was ratified by the assessment of stability and internal consistency. To assess stability (test-retest), the instrument was answered by parents/guardians twice with a 21-day interval. Instruments for assessing health outcomes should be reproducible over time, 22  denoting a deficiency in the instrument's content validity. 11,22 In studies of validation of questionnaires, EFA is employed to verify the connection that exists between the variable assessed and the individuals who responded the questionnaire. Usually, oblique rotation rather than orthogonal rotation is used for this purpose. It is reasonable to test the solutions provided by different types of oblique rotations. 25 In the present study, the promax rotation produced the most adequate solution and, thus, was used as the basis of the interpretation. In the present study, the value of CFI indicated that the data observed fitted the theoretical model.
The final methodological issue that deserves a discussion is the use of DAI for malocclusion assessment, rather than other available indices. DAI aggregates aesthetic and clinical characteristics numerically to provide a unique score that can be analyzed as a continuous or a categorical variable. 6,28 In comparison with alternative indices, DAI is easier to use and time saving during data collection. 28 Items 11 and 25 * The score for these items should be reversed.